Synergistic effect assessment of pollution and carbon reduction and pathway of green transformation at regional level in China

Promoting coordinated pollution and carbon reduction in this region is essential for China to achieve sustainable development and a green social transformation. This study employs a two-way fixed effect and intermediary effect model to examine the synergistic, dynamic evolution process and realization path between pollution reduction policy (RPP) and carbon reduction policy (RCP). Utilizing historical emission data and policy planning objectives, a LEAP provincial model is constructed under various scenarios to predict the synergistic effects of carbon emissions and air pollutant emissions. The findings reveal significant synergistic benefits from the two emission reduction policies: For every 1% increase in RPP, carbon dioxide emissions will decrease by 0.016%, and for every 1% increase in RCP, air pollutants will decrease by 0.375%. The synergistic effect of RCP on pollution reduction gradually strengthens over time, with three main pathways: reducing energy consumption intensity, optimizing industrial structure, and advancing technological progress. Additionally, the synergistic emission reduction effect in BTH is notably lower than in the YRD. Under the policy scenario, carbon emissions in the YRD and BTH will peak in 2027 and 2030, respectively. By 2035, the synergy level of carbon and pollutants in Beijing, Shanghai, and Tianjin will remain low (<0.5), while the other four provinces will maintain a high synergy level, indicating substantial potential for collaborative emission reduction.